Electric vehicles or hybrid vehicles are provided with drive motors. As technology of detecting a rotation angle of a rotator (output shaft) of a drive motor, technology using a resolver has been known.
Position detection by this kind of resolver is carried out by converting an output of a resolver to a rotation angle by an R/D (Resolver/Digital) converter, and a motor control device controls a drive current amount for controlling rotation of a drive motor in accordance with the rotation angle (for example, see Patent Document 1).
FIG. 8 of Patent Document 1 describes that a rotation angle of a motor is detected by a resolver, rotation angle information is converted by an R/D processing portion, then an output value of the resolver is corrected by a correcting portion, and a CPU controls a motor driver; and also describes that a correction value for correcting an output value of the resolver is stored in a PROM.